Comparison between Prediabetes Defined by Hemoglobin A1c (A1C) 5.7-6.4% and that Defined by Impaired Fasting Glucose (IFG) in a Japanese Population

Objective: To investigate prevalence and cardiovascular risk profiles of prediabetes defined by hemoglobin A1c (A1C) 5.7-6.4% and that defined by impaired fasting glucose (IFG) in Japanese. Subjects and Methods: We calculated the prevalence of isolated A1C 5.7-6.4%, isolated IFG, and overlap of A1C 5.7-6.4% and IFG and compared cardiovascular risk profiles of each group in non-diabetic Japanese 2,274 men and 1,417 women. Results: The prevalence of isolated A1C 5.7-6.4%, isolated IFG, and their overlapping was 6.1%, 11.9%, and 9.5%, respectively in men and 13.3%, 4.0%, and 6.4%, respectively in women. HDL cholesterol (p=0.004 in men and 0.03 in women), systolic blood pressure (p=0.047 in men and 0.0005 in women), and total bilirubin (p=0.0001 in men and 0.013 in women) were significantly lower in subjects with isolated A1C 5.7-6.4% compared with those with isolated IFG. Conclusions: Overlap of A1C 5.7-6.4% and IFG was not uncommon in Japanese. There were gender differences in the prevalence of isolated A1C 5.7-6.4% and isolated IFG. A1C 5.7-6.4% was associated with lower HDL cholesterol and lower bilirubin.